'use strict';

function double_to_one(collection) {

let arr=(collection+'');
console.log(arr);
let arr1=arr.split(',')
let result = arr1.map(function (x) {
  return Number (x);
})


console.log(result);
return result;
 
}
double_to_one([1, [2], [3, 4]]);
module.exports = double_to_one;
